Assessment of Antibiotic Resistance in Agricultural Production

Antibiotic resistance has become one of the most significant global threats to human health. The CDC reports at least 2 million cases a year have been found in the United States alone. Antibiotic drugs work on the microbial level to treat and prevent infections caused by bacteria, but the FDA reports that 70% of these infectious bacteria have become resistant to the antibiotics with which they are often treated. Widespread antibiotic use in animal production agriculture creates risk of direct exposure to antibiotic resistant pathogens and creates reservoirs of antibiotic resistance that may be transferred to pathogens through environmental contamination. To determine which animal production system had the highest frequency of antibiotic resistance genes, DNA was extracted from a panel of 140 Escherichia coli isolates and PCR was used to identify samples that contained the CTX and intL antibiotic resistance genes. We found the CTX antibiotic resistance gene in 32% of dairy cattle samples, 24% of beef cattle samples, and 50% of swine samples. We found the intL antibiotic resistance gene in 5% of dairy cattle samples, 0% of beef cattle samples, and 75% of swine samples. These results suggest that different animal production systems may foster antibiotic resistance at different rates with dairy cattle and swine having higher frequencies than beef cattle